The present invention relates to fish processing and more particularly to an improved method and apparatus for processing transverse fish body sections wherein a high intensity water jet knife traverses the fish section using computer generated position information obtained from video imaging such as a video camera, and wherein a support matrix such as a multiplicity of knife blade beams supports the fish section during high intensity water jet cutting. The beam system can have a sufficiently small cross-section normal to the line of sight so that it does not interfere with imaging of the fish section. Alternately, a darkened beam support can be used which reflects little or no light and is thus "invisible" to the video camera.
In the processing of fish such as tuna, it is common to freeze a catch of fish at sea, and to process the catch on shore. The processing normally involves manual operations of slicing the fish belly and the removal of viscera. The visceral cavity is then washed with water, and the tuna inspected for spoilage. The tuna is then usually cooked whole in a batch type procooking operation.
Manual prior art methods of processing tuna are described in greater detail in U.S. Pat. No. 3,594,191 issued to J. M. Lapeyre. That patent discloses cutting the tuna in lateral sections at spaced intervals and thereafter separating the edible loin portions to provide discrete cannable portions. A later U.S. Pat. No. 3,593,370 entitled "Method of Butchering Tuna" issued to J. M. Lapeyre, describes a process for processing such transverse tuna sections while frozen. The method of butchering frozen tuna included the subdivision of the whole fish into a plurality of transverse cross-sections and subsequently subdividing the cross-sections into frozen segments. The junctures between the sections were along lines generally parallel to the longitudinal axis of the fish and to the skeletal structure thereof. Each lateral fish section was skinned and the skinned sections were operated on to effect a separation of the scrap parts of the sections from the loin meat parts, while the latter were still in at least a partially frozen condition.
U.S. Pat. No. 3,800,363 issued to J. M. Lapeyre entitled "Tuna Butchering Method and System" describes an automated butchering method and system for separating the edible loin portions of transverse tuna slices provided by subdivision of a frozen whole tuna. Each transverse slice of the principal loin bearing section of a frozen tuna was scanned to produce electrical signals representative to the boundary between the edible loin portions and the contiguous waste meat portions. Control signals were then derived from the electrical signals for use in cutting for precise separation of the edible loin portions along the detected boundary. A photosensor array scanner was arranged to reflect light from the surface of a tuna slice and a provided light source. Electrical signals were provided by the sensor array of varying magnitude in accordance with the varying reflectivity of the slice surface being scanned. The electrical signals were processed by a threshold circuit which provided a threshold level above which signals were presumed to be representative of the lighter, edible loin portions and below which the signals were presumed to be representative of the relatively darker waste meat portions. The transformation of scanner output signals into control signals for the cutting apparatus was thought to be accomplished by a special purpose electronic controller or a suitably programmed computer to provide cutting control signals. Electrical output signals were also described as controlling operation of a cutting tool. The cutting apparatus for cutting the loin portions along predetermined boundaries was described as a high pressure water jet cutter which typically would operate at a pressure of about 30,000 to 75,000 psi and the water jet cutter was described as typically being mounted upon a movable head.
U.S. Pat. No. 4,738,004 also issued to J. M. Lapeyre has some similarity to the Lepeyre U.S. Pat. Nos. 3,593,370 and 3,800,363, but is primarily directed toward cooking or partial cooking of the transverse fish section prior to visual imaging so as to enhance the boundaries between the loin portions and blood-meat portions of the transverse fish section.
U.S. Pat. Nos. 3,594,191; 3,593,370; 3,800,363 and 4,738,004 are hereby incorporated herein by reference.
One of the problems not addressed in the above Lapeyre patents was the problem of supporting the transverse or lateral fish sections, when processing used a high speed, high pressure water jet cutting apparatus. Water jet knives typically employ a very high speed jet of pressurized water or like fluid which operates at a water pressure of up to 75,000 psi. When water jet cutters strike the transverse fish body section, there is a need to support the fish body section against the enormous force of the water jet knife, yet at the same time hold the lateral fish body section precisely so that error and waste are minimized. In short, the transverse fish body section must be precisely yet firmly supported during the cutting operation.
Another problem involves that portion of the water jet which travels downstream of the fish body section after the water jet passes through the fish body section removing a very small portion of the fish as the cutting progresses. The cut material and the high speed water would travel for many, many feet downstream of the target and would create a hazardous and messy condition if not controlled.
Yet another problem in processing fish relates to the video image which must be taken of the fish section. The knife must be precisely moved to cut the edible loin portions of the fish from the waste or lesser desirable portions thereof. A video image can be used but only the fish section needs to appear in the image. Any image other than the fish section causes confusion and error. In order to prevent the giving of false image information to the water jet knife, the fish body section must be photographed by a video camera and yet the support mechanism for the fish body section cannot interfere with that image created. When using a water jet knife, a high speed, high pressure water jet traverses the fish section. The water jet knife will desirably penetrate the fish section very quickly yet must continue downstream of the fish section unobstructed so that deflected water from the jet stream will not hit the fish section in an uncontrolled fashion that might move the fish section with respect to the knife destroying the precision of the operation and/or damaging the edible loin portion of the fish section during the process. The support mechanism for the fish body section must be precise, yet rugged, and preferably movable between the camera and water jet positions.